Kai Parker

Malachai "Kai" Parker is a major recurring character and the primary antagonist of the first half of the sixth season of The Vampire Diaries. Kai is the twin brother of Josette Parker, the older brother of Joey Parker and three deceased unnamed siblings, as well as Olivia Parker and Lucas Parker.
He is first seen trapped in the prison world with Damon Salvatore and Bonnie Bennett. Kai unwillingly forms an alliance with Damon and Bonnie, in effort to escape the world they are trapped in.
Eventually, after Damon returns to the world of the living, Kai and Bonnie are the only two left in the prison world. Later on, him and Bonnie attempt to escape the prison world, but Bonnie stores her magic in a teddy bear. Enraged by this, Kai takes Bonnie to his childhood home and cooks her a Thanksgiving meal. He eventually betrays Bonnie, taking the knife his sister's magic was stored in, stabbing Bonnie and taking the car he promised her.
Kai eventually resurrected himself, antagonizing the Mystic Falls Gang, seeking to kill his surviving siblings and merge with Jo, regardless of the consequences. However, in Prayer For the Dying, his younger brother Luke attempts to merge with him instead. Kai ultimately overpowered Luke and absorbed all his magic during the merge. Soon after, Luke's essence also merged with Kai, passing down his emotions and mellowing Kai out, making him less evil. He now works with the Mystic Falls Gang. However, he was left in the 1903 prison world in A Bird in a Gilded Cage.
Kai is a member of the Parker Family, and the new leader of the Gemini Coven.